On 08/19/2014 05:03 PM, Paolo Bonzini wrote: > Il 19/08/2014 10:50, Xiao Guangrong ha scritto: >> Okay, what confused me it that it seems that the single line patch >> is ok to you. :) > > No, it was late and I was confused. :) > >> Now, do we really need to care the case 2? like David said: >> "Sorry I didn't explain myself very well: Since we can get a single wrong >> mmio exit no matter what, it has to be handled in userspace. So my point >> was, it doesn't really help to fix that one very specific way that it can >> happen, because it can just happen in other ways. (E.g. update memslots >> occurs after is_noslot_pfn() and before mmio exit)." >> >> What's your idea? >> >>> I think if you always treat the low bit as zero in mmio sptes, you can >>> do that without losing a bit of the generation. >> >> What's you did is avoiding cache a invalid generation number into spte, but >> actually if we can figure it out when we check mmio access, it's ok. Like the >> updated patch i posted should fix it, that way avoids doubly increase the number. > > Yes. > >> Okay, if you're interested increasing the number doubly, there is the simpler >> one: > > This wastes a bit in the mmio spte though. My idea is to increase the > memslots generation twice, but drop the low bit in the mmio spte. Yeah, really smart idea. :) Paolo/David, would you mind making a patch for this (+ the comments in David's patch)? Please feel free to add my: Reviewed-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
